The overall goal of this revision application is to build an interdisciplinary research team capable of developing and utilizing quantitative, non-invasive technologies for studies of soft tissue (tendon to bone) healing with a focus on the rotator cuff. The proposed team would combine an expert in the field of tendon and tendon to bone healing, Dr. Soslowsky, with experts in the field of nuclear magnetic resonance (NMR) with proficiency in tendon and bone, Dr. Navon and Dr. Wehrli respectively, to address important health problems. More specifically, Dr. Soslowsky is the PI on an active NIH/NIAMS R01 grant (the parent grant) comparing the efficacy of various post-operative activity levels on tendon to bone healing following surgical repair in a rotator cuff animal model. Dr. Navon has developed a NMR double-quantum-filtered (DQF) method for quantifying tendon structure, with which he has performed both animal and human studies. Dr. Wehrli has developed a magnetic-resonance (MR) technique (virtual bone biopsy) for quantifying trabecular bone structure, with which he has done multiple human studies. This team is therefore uniquely positioned to develop non-invasive techniques for quantifying tendon to bone healing in the rotator cuff, as well as to use these techniques to compare treatments (e.g., post-operative activity) making the team an ideal fit for the Funding Opportunity Announcement (AR-08-001: NIAMS Building Interdisciplinary Research Team (BIRT) Revision Awards). As stated above, the parent grant compares the efficacy of post-operative activity protocols on tendon to bone healing in a rotator cuff animal model. More specifically, we have previously shown that reducing the level of post-operative activity, by immobilization, resulted in improved biological, structural and mechanical properties of the repaired tendon to bone insertion site compared to either cage-activity or exercise [1, 2]. Importantly, the improvement in tissue structural properties, collagen organization, preceded the improvement in mechanical properties. Thus, collagen organization may be an early indicator of tendon to bone healing, a finding which forms a basic premise for this revision application. If collagen organization can ultimately be quantified in vivo, it could be used as a critical assay to determine when the insertion site has healed enough so as to benefit from remobilization. This would have tremendous scientific and clinical implications. Unfortunately, the only methods currently available to quantify collagen organization in our model require tissue excision at sacrifice, and are therefore not transferable clinically. This represents a significant barrier to future success in this area that can be removed through this interdisciplinary collaboration. [unreadable] [unreadable] [unreadable]